pavilion angle vs. pavilion depth HUH?

[patric2007]

it seems from what ive read on this forum that the best pavilion angle for a RB is 40-41... my tiffany certificate list it using the term "pavilion depth percentage" ....(mine being 44.1)............................................................................why the different term and how do i go about finding the best stat for pavilion if they do not use the word"angle"? ....using Tiffanys wording ( depth percentage) what numbers should i look for...thanks

 

[Regular Guy]

Maybe someone else can do the conversion for you, but you can choose angle OR percent on this tool, enter the other data you need (crown angle, depth, table), and get the answer you''re looking for...

 

[avlis]

its not just a different word or term, they are two different measurements. in this picture,on the left of the girdle the angles are shown, on the right the percentages.

 

[oldminer]

IN THEORY, the percentages will give identical results as angles when one uses a trig calculator. IN REALITY, because of the software and limitaitions of Ogi or Sarin, the angles may be a bit more accurate in dexribing the actual diamond. Essentially both percentage or angle ought to work in a formula, but Garry found the angles worked a bit better. In my system, I used percentages because back when I made it, it was as reliable as any other set of parameters. They work pretty good, but I concur with Garry on the preference for using angles in the HCA>

 

[Regular Guy]

Continuing my role as interested observer...

I''d understood recent comments on this by JohnQ to be extended on this and clarifying.

Although I haven''t really understood what exactly % represented (percent of the total, top to bottom?), I''ve know them to stand in for angles. I''ve read Garry''s comments on the preference for angles and accepted them. But, in a webinar, JohnQ said a % is exactly fine. Later, I read where he clarified this, and it made sense to me.

Avlis..this explanation is I think simpatico with your diagram.

For the pavilion angle measurement...taken from the girdle to the bottom...however you measure it shouldn''t matter.

For the crown...the size of the table will impact the measurement of the crown angle at the girdle...and I think that generally less critical measurement will still vary in ways that % info is less sensitive to. And so here, you''d prefer the angle measure. But, % will do, while not picking up the variance for the table size.

Have I got that right?

Garry?

Regards,

 

[JohnQuixote]

Date: 9/12/2007 10:16:55 AM
Author: Regular Guy

But, in a webinar, JohnQ said a % is exactly fine. Later, I read where he clarified this, and it made sense to me.

Crown angle is needed because of the diamond''s table but we can judge pavilion angle by knowing pavilion % when no culet (pointed culet) is present. As Dave mentioned, normal scan tolerances apply.

Ira, it might have been this post, with a little more elaboration, which made sense to you (?)

 

[Regular Guy]

Date: 9/12/2007 12:33:22 PM
Author: JohnQuixote

Ira, it might have been this post, with a little more elaboration, which made sense to you (?)

Indeederino.

Maybe sometime we should do a review of search strategies of the rich & famous...which would need to include the mental recollections of the searcher, allowing the search to be successful.

Meanwhile...I think the ball is in Garry's court for both an acknowledgement and correction...unless rounding issues need still to be tied into a preference against %...and further...for a determination that...despite the importance of the pavilion angle, at least when no culet, the crown more uniquely, only, will benefit from an angle presented.

 

[bams0103]

Hi Avlis

Where did you get this diagram? And are these specs considered "ideal"? Based on what I read here, they seem broad to me.

Thanks!

 

[JohnQuixote]

I believe Avlis was just trying to show the difference between pavilion angle and pavilion depth measures for the OP.

Date: 9/13/2007 3:37:17 PM
Author: bams0103
Hi Avlis

Where did you get this diagram? And are these specs considered 'ideal'? Based on what I read here, they seem broad to me.

Thanks!

Indeed. Those are ye auld AGS proportions from over a decade ago, since revised and now out of date. In 2005 AGS moved to grading light performance based on all 57 facets of the diamond.